Patent GB-671928-A (GB)
Title: Improvements in or relating to hammers and stamps worked by elastic fluid under pressure
IPC: B21J7/24
Filed: 1948-10-28
Abstract: 671,928. Steam and other fluid-pressure hammers. MASSEY, Ltd., B. & S., and WELLS, L. W. Nov. 25, 1949 [Oct. 28, 1948], No. 27967/48. Classes 122(ii) and 122(iii) In steam hammers or stamps worked by elastic fluid under. pressure and fitted with expansion valve gear in which rotation of the valve during the downstroke of the hammer cuts off the ports admitting steam to the top of the hammer and thereby allows the steam already in the cylinder to be used expansively, provision is made to enable the movement imparted to the valve by the handlever to be increased whereby the rotation of the valve which had previously cut off the admission of steam brings the steam ports in the valve into communication with supplementary ports in the valve cylinder liner thereby continuing the admission of steam to the upper side of the hammer piston throughout the whole of the downstroke. A control valve 1 attached to a spindle 2 operates in a valve chest C and is movable axially by means of a manually operated handlever 3 having two alternative lower positions dependent on the setting of a two-position throw-over stop 13, and radially by means of a roller 5, operatively connected by a spring-returned link system to the spindle 2, engaging a cam surface 12 on the tup 4. The valve 1 has peripheral grooves 19, 28 therein serving as passages to establish communication as desired between the valve chest steam inlet passage 14 and passages 15, 16 leading to the top and bottom respectively of the hammer cylinder A, and exhaust ports 26 for exhausting the space above the hammer piston B on its upstroke. Atmospheric exhaust passages 17, 18 are provided in the valve chest C which is also fitted with two liners 22, 21 having ports 25, 27, 32 and 33, 34 respectively, co-operating with cylinder supply and exhaust ports in the valve. To strike a blow using the steam expansively the throw-over stop 13 is set in its upper position so as to limit the downward movement of the lever 3 which movement raises the control valve to the position shown in Fig. 5, thus admitting steam above the hammer piston B through passages 14, 19, port 32 and passage 15 and exhausting from the bottom of the cylinder through passage 16, ports 33, 34 and passage 18. When the hammer has descended a predetermined amount the control valve is rotated due to the cam surface 12 on the tup engaging the roller 5, communication between passages 19 and ports 32 ceases and cut off takes, place. To strike a dead blow the throw-over stop 13 is set in its lower position thus increasing the upward movement of the control valve which, when the lever 3 is down, occupies the position shown in Fig. 7. steam is admitted to the top and exhausted from the bottom of the cylinder as before but when the valve is rotated by the tup instead of the steam being cut off it is still supplied to the top of the cylinder through passages 19 and ports 25 and also through passages 28 and ports 32, Fig. 8, and thus the flow of steam is maintained throughout the whole of the downstroke of the hammer. The hammer piston is raised by steam used expansively and held at the top of its stroke by steam pressure in the normal manner. Provision is made to hold the hammer down by additional peripheral grooves in the valve which, when the hammer is down and the lever 3 is set to locate the valve in a particular axial position connect passage 14 with ports 32 and allow steam pressure to be supplied to the top of the piston through passage 15. Specification 26452/06, [Class 122(iii)is referred to.